Furniture pieces are typically manufactured and assembled at a factory and then shipped as a complete unit to a distributor or customer. The sections of the furniture piece are typically joined together using bolts that extend through predrilled holes in wooden or metal parts of the sections. Upholstery is used to cover the furniture sections, including the bolts and wooden or metal parts of the sections. The completed furniture piece is typically too heavy to be handled by a single individual and too large to be maneuvered through some doorways and stairwells. As a result, customers may limit the furniture that they choose to purchase or may object to additional charges required for third-party delivery of the furniture. In addition, it is difficult to efficiently pack assembled furniture pieces due to their size, shape and the fragility of the upholstered surfaces. Damage to any portion of the furniture piece typically requires the entire furniture piece to be shipped to a factory for repair.
One approach to this problem has been through the use of ready-to-assemble (RTA) furniture that provides increased options for storage, delivery and assembly of the furniture. For instance, U.S. Pat. No. 5,338,095 to Laughlin et al. discloses a furniture piece that relies on interlocking frame members to secure the modular sections together. The interlocking joints are designed to be easy to assemble. In one instance, a pair of combined wedge and parallelepiped shaped sockets 64 defined at the lower ends of a pair of vertical side members 72 of a backrest member 26 allow the backrest member to be secured to a pair of rail members 50, as shown in FIG. 3. Despite the ease of assembly, the furniture disclosed by Laughlin, and other conventional RTA furniture, can suffer from looseness in the fit between the modular sections that results in instability. For example, a looseness in fit due to repetitive loading can result in wobble or rocking of the backrest relative to the base of the furniture piece. Laughlin attempts to solve this problem with the addition of a pair of thumbscrews 96 that secure the backrest member to respective wing portions 100 of the seat. However, a pair of unsightly flaps in the upholstery are necessary to secure the thumbscrews and the thumbscrews require the presence of the wing portions for attachment, thereby limiting aesthetic design variations.
Attempts have been made to eliminate the problem of instability through other variations in the method of assembling, or fastening, the modular pieces together. For instance, U.S. Pat. No. 5,551,757 to Glover discloses a fastening system for RTA furniture. The fastening system employs side-support rails secured to the arm sections of the seat which allow either a seat platform or a foldout bed platform to be secured within the furniture piece. A pair of hooks are mounted to a back section and the back section is connected to the side-support rails and between a pair of armrests by mounting the hooks on a pair of engagement pins of the side-support rails. The back section is further secured using hard bolts 88 that are fed through the back section and into the armrests, as shown in FIG. 2. Although the fastening system of the Glover patent increases the rigidity of the assembled back section, the back section is divided into two portions that can be disengaged to allow access for insertion of the hard bolts into the armrests. This two-piece back section is more costly to produce than a conventional sofa back section.
It would be advantageous to have a frame assembly for RTA modular furniture that allows the furniture to be quickly assembled and yet has relatively rigid construction without sacrificing aesthetic appeal. It would be further advantageous if the backrest of the furniture could be rigidly secured to the base of the furniture piece using the frame assembly without undue visible alterations in the appearance of the backrest or base of the furniture piece. It would be further advantageous if the frame assembly were adaptable to different aesthetic variations of furniture and different types of furniture, such as sleeper sofas.